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2015-01-04 22:45:06 -0500 asked a question Directory of executables of ROS nodes compiled with Catkin

I have built ROS node that uses openCV and that needs to load some specific files during execution. The files need to be in the 'current directory' in usual OpenCV implementation, which I believe is the directory of the compiled ROS nodes.

  • Is that correct?
  • Where is it located?

The exact code I am talking about can be found on the link given above, where two files, "haarcascade_frontalface_alt.xml" and "haarcascade_eye_tree_eyeglasses.xml" have to be loaded by the instructions

face_cascade.load( face_cascade_name )
eyes_cascade.load( eyes_cascade_name )
2015-01-04 15:08:18 -0500 answered a question help with rosrun image_transport

image_transport is a different ROS package. Your project is named image_transport_tutorial and you simply need to launch

rosrun image_transport_tutorial my_publisher path/to/some/image.jpg

in order for it to work. You have to make sure that your project is in ROS working path.

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2015-01-04 14:45:15 -0500 asked a question Black image for an Image publisher with image_transport

I made a node retrieving an image with openCV explained on this ROS tutorial. The image is ten converted into a format suitable for ROS, using CV_bridge functions.

Problem is, there is no image that are published at all on the \camera topic. I tried visualizing it using

rosrun image_view image_view

But the only thing that appear is a black image. I also tried using rviz camera, but nothing appears; rviz indicate that no image is received:

image description

Here is the code of the publisher:


And here is the CMakeLists.txt file:

image description

I made a standalone version of the code for openCV, and it display image correctly using imshow. I do believe that the problems lies in the conversion of the openCV image to the format required by the ROS nodes, but I do not know where to look to solve such problem.

2015-01-03 13:42:59 -0500 answered a question Fail to rosmake

You don't seem to have beginner_tutorials in your ROS_PACKAGE_PATH.

You should probably add this line to your ~/.bashrc (after the line which sources the ROS setup.bash):

export ROS_PACKAGE_PATH=/path/to/beginner_tutorials:${ROS_PACKAGE_PATH}
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2014-12-14 03:04:43 -0500 answered a question PyQtGraphDataPlot and MatDataPlot fail to load

You need to manually install the PyQtGraph.

  1. Download the Debian/Ubuntu package on the PyQtGraph website
  2. Go to the download directory and type (my version of PyQtGraph is 0.9.8)

dpkg -i python-pyqtgraph_0.9.8-1_all.deb

You can now use

rqt_plot "topic name"


rosrun rqt_plot rqt_plot "topic name"

image description

There is no more errors.